Clock with separate day and night dials



y 1955 P. A. SIDELL CLOCK WITH SEPARATE DAY AND NIGHT DIALS Filed Oct. 4, 1963 2 Sheets Sheet l 7 Fl III Ill mmvroze. P627429 4 5256/! y 7, 1965 P. A. SlDELL 3,196,604

CLOCK WITH SEPARATE DAY AND NIGHT DIALS Filed Oct. 4, 1963 '2 Sheets-Sheet 2 United States Patent 3,196,6tl4 QLQCK WITH SEPARATE DAY AND NIGHT DIALS Phiiip A. Sidell, West Hartford, Conn, assigncr to The lingraharn Company, Bristol, Conn, a corporation of (Donnecticut Filed on. 4, 1963, Ser. No. 313,915 9 Claims. or. ss-sa This invention relates to clocks in general, and to dayand-night readable clocks in particular.

The present invention is concerned with clocks the dials of which are readable in day or artificial light and, by contained illumination, are also readable in the dark, as in an unlighted room between dusk and dawn, for eX- ample. Some of the prior dial-illuminated clock are of a type having a light-permeable, mostly translucent, dial which for reading in the dark is illuminated from the rear either directly from a small electric light bulb or through intermediation of a light-distributing lens, with the bulb being either on all the time or switchable on and ed. While prior clocks of this type are highly useful, they do impose some limitations on the arrangement, styling and dimensions of the hour indicia on the dial in order to be easily readable at all light levels including the dark. These limitations are particularly apparent in clocks the translucent dials of which are rear-illuminated from a very weak light source, such as that afforded by miniature electric light bulbs, for example, which not only are highly economical to operate but also furnish that low level of dial illumination in the dark which amounts to no more than a soft glow and is preferred by most. Thus, it is on the one hand the preferred low level of dial illumination and on the other hand the required fair readability of the dial in the dark which call for rather large and bold hour indicia on the dial and, hence, preclude many desirable stylings and dimensions of these hour indicia for daytime reading. Moreover, the dial illumination from the aforementioned weak, but highly economical, light source compels the arrangement of the hour indicia on the dial within a comparatively small area for ready readability in the dark, whereby the arrangement of the hour indicia affects the size, and also shape, of the clock in a limiting way in order to permit a dial design which is truly functional as well as in good taste.

It is an object of the present invention to provide a clock of this type the dial of which is clearly readable at all light levels including the dark, yet the dial may be styled in virtually the same infinite ways as that of a nonilluminated dial clock in the matter of its size and shape and in the arrangement, style and dimensions of the hour indicia thereof, whereby the remainder of the clock may also be sized and styled as widely as non-illuminated dial clocks.

It is another object of the present invention to provide a clock of this type with separate dials for day and night observation, respectively, of which the night dial may be rear-illuminated at night if desired, but preferably at all times, yet only the day dial will be visible to an observer in daylight, or in artificial light of comparable intensity while the day dial is invisible to an observer in the dark.

With the day dial being thus completely independent of the night dial, the day dial and the remainder of the clock may be styled, shaped and dimensioned in the aforementioned virtually infinite ways of a non-illuminated dial clock, while the night dial may be styled, shaped and also dimensioned for best effect as such and observation in the dark.

It is a further object of the present invention to provide a clock of this type with the aforementioned separate day and night dials, of which part of the day dial constitutes the observable night dial by serving as a screen onto the rear face of which are projected the images of the rearilluminated night dial hour indicia behind the day dial, with this projection-screen part of the day dial being translucent so that the rear-projected hour indicia images on the day dial are invisible on the front surface thereof in daylight or in artificial light of comparable intensity but are clearly visible on the front face of the day dial in the dark, while the hour indicia of the day dial are pro vided on another part of the latter which in the real is shielded from all light serving for the rear-illumination of the night dial and, hence, are invisible in the dark.

Another object of the present invention is to provide a clock of this type with the aforementioned separate day and night dials, of which the hour indicia of the night dial are either in the form of opaque characters, or in the form of light-passing cutouts in an opaque mask, behind the day dial, with the opaque characters, if used, beoing provided either on the back face of the day dial or on the front face of a light-distributing lens of the dial rear illumination system, and the cutouts, if used, being provided either in an opaque coating on the back face of, or in a separate opaque mask behind, the day dial, or in an opaque coating on the front face of a lightdis-tributing lens of the dial rear illumination system.

Other objects and advantages will appear to those skilled in the art from the following, considered in conjunction with the accompanying drawings.

in the accompanying drawings, in which certain modes of carrying out the present invention are shown for illustrative purposes:

FIG. 1 is a front view of a clock embodying the present invention;

FIG. 2 is a partial side view of, and partial section through, the clock, with the section taken substantially on the line 2-2 of FIG. 1;

FIG. 3 is another front view of the clock, showing the same as it appears in the dark;

7 FIG. 4 is a partial side view of, and partial section through, a clock embodying the present invention in a modified manner;

FIG. 5 is a fragmentary front View of the modified clock of FIG. 4 as it appears in the dark;

FIG. 6 is a front view of a clock embodying the present invention in a further modified manner;

FIG. 7 is a partial side View of, and partial section through, the modified clock of FIG. 6; and

FIG. 8 is a front view of the modified clock of FIG. 6 as it appears in the dark.

Referring to the drawings, and more particularly to FIGS. 1 and 2 thereof, the reference numeral 19' designates a clock having a casing 12 with a time dial 14 and the usual transparent crystal to in front thereof, as well as a movement which is preferably powered by a synchronous motor (neither shown) and includes the usual hour, minute and second shafts 18, 2t), 22 and in this instance also an alarm shaft 24. The shafts 18, 2t and 22 carry hour, minute and second-sweep hands 26, 28 and 30, re-

greases 3 spectively, while the shaft 24 carries an alarm hand 32, with all hands being in front of the time dial 14-.

The time dial 14 comprises a plate 34 bearing time indicia 36 which in this instance are in the form of arabic numerals denoting the hours from 1 to 12. The hour indicia 3d are provided on the dial plate 34 in any suitable manner so .as to be clearly readable on the front face of the dial plate. In the present instance, the hour indicia 36 are carried by the dial plate 34 on the front face 33 thereof, and they may be applied thereto in any conventional manner such as by printing, for example.

The present clock it) is of the illuminated type so as to be readable in the dark. To this end, the dial plate 34 is of ligh-permeable, and in this instance translucent, material such as plastic, for example, and the same is illuminated from the rear by an illuminator 40 in the casing 12. The illuminator 4d provides a suitable light source in the form of a preferred electric light bulb 42 (FIG. 2), and preferably provides further a light-distributinglens 34- employing the well-known edge-lighting principle. The lens 44, which in this instance is generally cup-shaped and has a flat bottom or lens plate 46 and a preferably cylindrical rim 43, may be made of any of 'the materials normally employed for edge-lighted dials,

such as transparent plastic, for example. The free edge b of the lens rim 4% is over the greater part of its circular extent provided with notches 52 of varying depth, while the back face 54, and in this instance also the front face 56, of the lens plate 46 have indentations 58 and dd, respectively, in the form of concentric grooves of triangular cross-section. The light bulb 42, which is received in a suitable socket formation 62 in the lens rim 4%, is by conductors 64 conveniently connected inside the casing 12 with the usual core (not shown) that supplies the operating current to the synchronous motor. Of course, a different-type bulb may be battery-powered in a non-electric clock. Light rays emanating from the bulb 42 pass circumferentially in the lens rim 4-8 where they are reflected by the notches 52 in generally axial direction and pass into the plane of the lens plate 46 where they are again reflected in generally axial direction by the indentations 58 and 64) in the back and front faces thereof. Part of these reflected light rays pass directly to the front face of the lens plate 46 while the remaining part of these light rays pass to the back face of the lens plate where they are again reflected by a reflecting and diffusing surface 66 in general axial forward direction, so that all light rays will finally pass to and through the front face 56 of the lens plate from which they emerge as visible light. The reflecting and diffus ing surface 66 may be provided in any suitable manner such as by a suitable coating on the back face of the lens plate 46 or by a separate disc element thereat.

The illuminator id is held in place in the casing 12 in any suitable manner (not shown).

In accordance with the present invention, there is provided a night dial 70 (FIG. 3) which is separate from the described dial 14 and is rear-illuminated by the illuminator 49, while provision is made to shield from the rear illumination the dial 14 so that the same may not be read in the dark and, hence, may aptly be termed a day dial. The night dial 7t comprises another set of hour indicia '72 behind the translucent dial plate 34 (FIGS. 2 and 3), and further includes a part of the dial plate 34 and also the illuminator an. The aforementioned shielding provision for the day dial 14 is in this instance an opaque mask 74 (FIG. 2) which is located immediately behind the dial plate 34, and preferably covers, and hence shields from the rear illumination, the entire dial plate except for portions thereof that are exposed to the rear illumination through apertu fes and cutouts in the mask '74. One of these apertures,

identified by the reference numeral 76, is arranged centrally of the mask 74 and is in this instance of circular outline, with the mask aperture 76 being in any event sufficiently small to be outside the confines of that part of the dial plate 34 on which the hour indicia 36 of the day dial is are located (FIGS. 1 and 2), but being sufficiently large to expose to the rear illumination that part of the dial plate 34 within the confines of which the hands 26 to 32 extend (FIGS. 2 and 3). The hour indicia 72 of the night dial are in this instance formed by cutouts in the mask '74 around the center aperture '76 therein, with these cut-outs having the exemplary configurations shown in FIG. 3, namely the roman numerals Ill, VI, IX and X11 and bars which are arranged to denote the hours for 1 to 12. Here again, these cutouts are arranged on the mask 74.- outside the confines of that part of the dial plate 34 on which the hour indicia 35 of the day dial 1 5 are located.

With the clock being in the dark and with the rear illumination on, the clock will have the appearance shown in FIG. 3. Thus, the clock case 12, which is shown in phantom dot-and-dash outline in FIG. 3, is either imperceptible or barely perceptible by an observer depending whether it is totally dark or less than totally dark, and the hour indicia 36 on the day dail 14, being shielded from the rear illumination as described, are imperceptible by the observer. However, the light emanating from the lens 44 passes through the center aperture '76 and surrounding cutouts 72 in the mask '74 and against the translucent dial plate 34 and thus projects the images 7% and 8th of this aperture and cutouts against the back face of the dial plate, with the translucen-cy of the latter and the level of the rear illumination being such that these images are clearly discernible at the front face of the dial plate in the manner shown in FIG. 3. The images 78 and 89 of the mask aperture and cutouts 76 and 72 thus discernible at the front face of the dial plate in the otherwise dark surroundings are seas of light which, however, are sharply defined in their outlines that correspond quite closely to the respective mask aperture and cutouts. Also, with the hands 26 to 32 being in front of the lighted dial area 755, their outlines are clearly discernible to the observer (FIG. 3) who, therefore, may readily read the correct time.

Preferably, the area of the lens plate as is kept at a minimum at which it will distribute the most even and concentrated light from the bulb of the strength used. In this instance, the area of the lens plate as is just sufiiciently large to illuminate the outermost margins of the discernible night dial '70, i.e., the outer ends of the cutouts 7 2 in the mask 74 (FIG. 2).

it is further preferred that the night dial 7i), if rearilluminated in daylight, remains invisible, or substantially invisible, at the front face of the dial plate 34, whereby the day dial 14 will be readable at a glance in the accustomed manner and without any possible confusion from the night dial. This is achieved, at the usual level of translucency of the dial plate, by keeping the rear illumination at a level sufiiciently low so that the lighted areas of the night dial on the front face of the dial plate appear in the dark as though glowing rather softly. The relatively low level of rear illumination thus required may readily be achieved with a miniature electric bulb 42 which is so highly economical to operate that the same may remain lighted day and night and makes an on and off switch entirely unnecessary. In thus kee ing the bulb 42 lighted continuously and keeping the rear illumination at the low level described, the unique feature of the separate day and night dials is carried even further to the extent where one dial disappears from view when the other dial comes to view, and vice versa, save for transitory periods when the light outside the clock is in the twilight zone or in intensity comparable to twilight.

In providing the clock with separate and independent day and night dials in accordance with the present i11- vention, there is this further important advantage that the day dial and the remainder of the clock may be styled, shaped and dimensioned in the virtually infinite ways of a single-dial clock, while the night dial may be styled, shaped and also dimensioned for best effect as such and observation in the dark.

While in the described exemplary clock In the nightdial hour indicia '72 are advantageously arranged inside the dial plate area on which the day-dial hour indicia as are located so as to have the same hands available for reading the correct time both in daylight and in the dark, it is, of course, fully within the purview of the present invention to arrange the night-dial hour indicia outside the dial plate area on which the day-dial hour indicia are located, and to concentrate the rear illumination on the night-dial hour indicia from an adjacent ringshaped light-distributing lens. In that case, the sole hands of the clock may, for time reading in the dark, be illuminated by light piped thereto in Well known manner, or additional illuminated hand means may be resorted to. Further, while the exemplary night-dial hour indicia are arranged circularly, they may obviously be arranged ovally or in any other form.

Reference is now had to FIG. 4 which shows a clock ltla that embodies the present invention in a modified manner. Thus, the modified clock a differs from the described clock 10 of FIGS. 1 and 2 primarily by having the night-dial hour indicia 72a provided on the front face 55a of the lens plate 46a, with the central aperture 76a in the mask 74a being inwardly spaced from the day-dial hour indicia 3on1 on the dial plate 34a, and being sufficiently large so that the hour indicia 72a are within its confines. The clock Ittta may in all other respects be exactly like the clock It of FIGS. 1 and 2. The night-dial hour indicia 72a are in this instance opaque elements applied to the front face 56a of the lens plate in any suitable manner, as by printing, for example, with only the back face 54a of the lens plate tea having in this instance light-defiecting indentations 58a, although the front face of the lens plate may have similar indentations outside the area thereof on which the hour indicia 72a are located.

With the hour indicia 72a arranged on the lens plate 46a in the form of opaque characters, their projected images Etta on the translucent dial plate 34a appear on the front face thereof in the dark as dark shadows which in the surrounding glow of the image 7811 of the mask aperture 76a rather sharply define the outlines of the hour indicia 72 a on the lens plate. The night dial We thus has in the dark the appearance shown in FIG. 5.

Reference is now had to FIGS. 6 and 7 which show a clock ltlb that embodies the present invention in another modified manner. Thus, the present clock 1% differs from the described clocks lit and ltla primarily by having the night-dial hour indicia 72b provided on the back face of the dial plate 34b, with the central aperture 76b in the mask 74b being sufiiciently large so that the hour indicia 72b are within its confines. The hour indicia 721) are in this instance opaque elements applied to the back face of the dial plate 34!) in any suitable manner. With the hour indicia 72b arranged on the back face of the dial plate 34b in the form of opaque characters, their projected images hill) on the front face of the dial plate appear in the dark as dark shadows which in the surrounding glow of the image 7% of the mask aperture 76b rather sharply define the outlines of the hour indicia 725 on the dial plate. The night dial 7012 thus has in the dark the appearance shown in FIG. 8.

The present exemplary clock ltlb is further indicative of the wide possibilities of styling, shaping and dimensioning the day dial and the rest of the clock in the virtually infinite ways of a single-dial clock without any real restriction from the night dial. Thus, the casing 12b of the clock is quite large and elongated horizontally in good taste with the exemplary oval arrangement of the day-dial hour indicia 36b which themselves are rather prominent in size and general appearance, while the night dial (FIG. 8) is in its size and also general appearance hardly in generally accustomed good harmony with the rest of the clock which, however, is of no consequence because the rest of the clock is invisible, or substantially invisible, in the dark.

The invention may be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

What is claimed is:

1. In a clock, the combination of a first dial having plate means of which a first plate area is light-impermeable and the remaining plate area is translucent, with said plate means having front and back faces and hour indicia on said first plate area visible and indivisible at the front face thereof in daylight and in the dark, respectively; light means behind said plate means for illuminating the back face thereof; and a night dial having other hour indicia and including said light means and translucent plate area, said other hour indicia being between said light means and said translucent plate area and confronting the latter for projection of their images thereagainst, and the translucency of said remaining plate area and the intensity of its rear illumination are such that said images are visible and substantially invisible at the front face of said plate means in the dark and in daylight, respectively.

2. In a clock, the combination of a first dial having a translucent plate with front and back faces and hour indicia on a first area of said plate visible at the front face thereof in daylight; light means behind said plate for illuminating the back face thereof; means between said light means and first plate area shielding the latter from illumination by said light means to confine the illumination to the remaining plate area; and a night dial having other hour indicia and including said remaining plate area and light means, said other hour indicia being between said plate and light means and confronting said remaining plate area for projection of their images thereagainst, with the translucency of said plate and the intensit of its rear illumination being such that said images are visible and substantially invisible at the front face of said plate in the dark and in daylight, respectively.

3. The combination in a clock as set forth in claim 2, in which said shielding means is an apertured opaque mask adjacent the back face of said plate.

4. The combination in a clock as set forth in claim 2-, in which said shielding means is an opaque coating on the back face of said plate, with said coating omitted on said remining plate area to expose the same to said rear illumination.

5. The combination in a clock as set forth in claim 2, in which said shielding means is an opaque mask adjacent the back face of said plate, and said other hour indicia are cutouts in said mask.

6. The combination in a clock as set forth in claim 2, in which said other hour indicia are opaque elements on the back face of said remaining plate area.

7. In a clock, the combination of a first dial having a translucent plate with front and back faces and hour indicia on the front face of a first area surrounding a central area of said plate; means including a light-distributing panel lens in back of said plate for illuminating the back face of said plate; means between said illuminating means and first plate area shielding the latter from said rear illumination to confine the same to said central plate area; and a night dial having other hour indicia and including said central plate area and illuminating means, said other hour indicia being between said plate and illuminating means and confronting said central plate area for projection of their images thereagainst, with the translucency of ameaoa said plate and the intensity of its rear illumination being such that said images are visible and substantially invisible at the front face of said plate in the dark and in daylight, respectively. V 8. The combination in a clock as set forth in claim 7, in which said pane-l lens has a light-emitting front face, and said other hour indicia are opaque elements on the front face of said panel lens.

9. The combination in a clock as set forth in claim 8,

83 References Cited by the Examiner UNITED STATES PATENTS LEO SMi'LOW, Primary Examiner.

in which said panel lens is substantially of the size of said 10 P OBERT L EVANS Exllminer central plate area and confronts the same. 

1. IN A CLOCK, THE COMBINATION OF A FIRST DIAL HAVING PLATE MEANS OF WHICH A FIRST PLATE AREA IS LIGHT-IMPERMEABLE AND THE REMAINING PLATE AREA IS TRANSLUCENT, WITH SAID PLATE MEANS HAVING FRONT AND BACK FACES AND HOUR INDICIA ON SAID FIRST PLATE VISIBLE AND INDIVISIBLE AT THE FRONT FACE THEREOF IN DAYLIGHT AND IN THE DARK, RESPECTIVELY; LIGHT MEANS BEHIND SAID PLATE MEANS FOR ILLUMINATING THE BACK FACE THEREOF; AND A NIGHT DIAL HAVING OTHER HOUR INDICIA AND INCLUDING SAID LIGHT MEANS AND TRANSLUCENT PLATE AREA, SAID OTHER HOUR INDICIA BEING BETWEEN SAID LIGHT MEANS AND SAID TRANSLUCENT PLATE AREA AND CONFRONTING THE LATTER FOR PROJECTION OF THEIR IMAGES THEREAGAINST, AND THE TRANSLUCENY OF SAID REMAINING PLATE AREA AND THE INTENSITY OF ITS REAR ILLUMINATION ARE SUCH THAT SAID IMAGES ARE VISIBLE AND SUBSTANTIALLY INVISIBLE AT THE FRONT FACE OF SAID PLATE MEANS IN THE DARK AND IN DAYLIGHT, RESPECTIVELY. 